"Soil release" is a general term used to describe a class of textile finishes which make it possible to release soil from fabrics by ordinary washing and they are especially designed to work on polyester fabrics. The soil release systems do not prevent soil from entering the fabric but they simply allow soil to leave the fabric faster. All soil release systems make the fabric hydrophilic (water accepting) and oleophobic (oil releasing)--to let water in and to keep oil out. Thus, soil release fabrics tend to resist oil-borne stains and permit water to enter for stain removal under ordinary laundering conditions.
The treatment of various textile fabrics with fluorochemicals to impart water and oil repellency has been known to those in the art for several years. Furthermore, certain fluorochemical polymer emulsions impart soil release properties, particularly to nonwoven materials. Durable soil release properties after repeated laundering cycles are assured by said fluorochemical polymer emulsions when used in connection with nonwoven and other materials which do not contain an adhesive binder thereon. However, in accordance with the present invention, it has been found that if nonwoven materials already containing a binder are treated with a fluorochemical soil release agent alone, it does not impart durable soil release properties to the fabric on repeated laundering cycles and, in fact, a substantial proportion of said soil release properties is lost after only two or three laundering cycles. Nonwoven fabrics which have been known for some time have been made from synthetic fibers such as polyester and polyester/rayon fibers. Generally, these fabrics are produced by forming a web of fibers and applying an adhesive binder to the web to hold the fibers together and provide strength. In some instances a fibrous web is fluid rearranged and then resin binder added to form a useful, coherent nonwoven fabric. In such a process, it has been surprisingly found, in accordance with the present invention, that if a fluorochemical soil release agent is added together with a binder and a cross-linking agent, that durable stain release properties on laundering are imparted to the resulting fabric. In this connection, applicant has achieved a soil release fabric durable through ten laundering cycles. In accordance with the present process there is substantially no chemical reaction between the adhesive binder and the fabric to which it is applied. However, it is believed that chemical bonding takes place between the binder, the cross-linking agent and the soil release agent.
The Schultz et al. U.S. Pat. No. 3,816,167 relates to a process for making a non-cellulosic synthetic fiber textile both soil resistant and durably soil releasing on laundering, comprising treating the textile with a soil release finishing composition consisting essentially of a fluoroaliphatic group containing soil release polymer and a polyalkylene glycol cross-linked in situ by an aldehyde-containing prepolymer. In said Schultz method the fluoroaliphatic soil release agent is actually reacted on the surface of the fibers, with the polyalkylene glycol but no binder is used. In the case of the present invention, on the other hand, a binder is used as well as a cross-linking agent. This provides superior results to those obtained when a cross-linking agent, but no binder is used.
A number of patents have issued directed to methods of assuring soil release from textiles, but none of said patents discloses the present method of incorporating a soil release agent and a cross-linking agent in an adhesive binder prior to application to the textile. A list thereof is as follows: U.S. Pat. No. 3,950,298; U.S. Pat. No. 4,330,588; U.S. Pat. No. 3,944,527; U.S. Pat. No. 3,995,085; U.S. Pat. No. 3,896,035; U.S. Pat. No. 3,987,227; U.S. Pat. No. 4,318,956; U.S. Pat. No. 3,816,229; and U.S. Pat. No. 4,329,391.
The present invention is most preferably used when it is desired to impart good soil release properties to entangle fiber polyester nonwoven fabrics to which an adhesive binder is normally applied to hold the fibers together and to provide strength. It has now been surprisingly found that if a soil release agent and a cross-linking agent are incorporated in the binder, that the resultant fabric is durably soil releasing on laundering. This is surprising in view of the fact that no durably soil releasing properties on laundering are obtained if a fabric, already containing a binder, is post-treated with a soil release agent alone.